1. Field of the Invention
This invention relates to stirring apparatus for fluids, slurries and powders, such as a polymerization reaction apparatus for preparing polymers from polymerizable organic compounds such, for example, as vinyl- and conjugated diene-series hydrocarbons. More specifically, the invention relates to a novel stirring apparatus so designed that the rate of heat exchange with materials being processed can be increased and the attachment of polymers, gells, crystalline solids and other solids to stirring members and to the inner wall of a container can be prevented. Rate of heat exchange and attachment have frequently posed problems in the operation of stirring apparatus.
2. Description of the Prior Art
In the operation of a stirring apparatus, a so-called close-clearance method or heating surface scraping method has generally being employed for the purpose of increasing the rate of heat exchange between a heating surface, such as the apparatus wall, and a material being treated, in which a stirring member is operated in very close proximity to the heating surface whereby the material being treated and located adjacent the heating suface is scraped by the stirring member. This type of apparatus has a remarkable effect in increasing the heat exchanging rate as is well known, and also makes a great contribution to the prevention of attachment of the material being treated to the apparatus wall. However, in conventional appararatus of this type, while the purposes of increasing the rate of heat exchange with the apparatus wall and preventing the attachment of material to the apparatus wall are attained, such effects cannot substantially be expected between the stirring member and the material being treated. On the other hand, with reference to the stirring member, a so-called self-cleaning type stirrer has been materialized especially from the attachment prevention point of view, which is composed of a plurality of stirring members, so that the material attached to the surface of one stirring member may be removed therefrom by the other stirring member. However, such a stirrer is restricted to special shapes and only a very few stirrers of this type are being put in practical use. Further, in considering generally the prevention of material attachment, the attachment of material not only to the stirrer but also to the apparatus wall should be prevented concurrently. The conventional apparatus of the type described have had the disadvantage that the effective volume of the apparatus actually occupied by a material is very small due to the limitation imposed on the structure of the stirrer. Little of the conventional apparatus has been satisfactory in respect of the requirement that both the apparatus wall and stirrer are self-cleaned completely concurrently and that the effective volume of the apparatus occupied by a material is large. Stirring is required to attain many purposes, i.e., not only the purpose of increasing the heat transfer rate and preventing the attachment of material, referred to hereinbefore, but also the purpose of making more uniform the concentration and temperature of a material being treated, increasing the moving speed of the material, securing a sufficient retention time of the material and obtaining a uniform distribution of the material; but none of the conventional apparatus has been satisfactory in concurrently attaining all of these purposes.